docs: def graph_val_dump(self):
          """Yield the entire contents of the graph_val table."""
          self._flush_graph_val()
          for (graph, key, branch, turn, tick, value) in self.sql('graph_val_dump'):
              yield (
                  self.unpack(graph),
                  self.unpack(key),
                  branch,
                  turn,
                  tick,
                  self.unpack(value)
              )